Two-cycle internal combustion engine



June 28, 1966 K. T. J. HENRIKSON 3,257,996

TWO-CYCLE INTERNAL COMBUSTION ENGINE 2 Sheets-Sheet 1 Filed June 18, 1964 //'2 van fo r June 28, 1966 K. T. J. HENRIKSON 3,

TWO-CYCLE INTERNAL COMBUSTION ENGINE 2 Sheets-Sheet 2 Filed June 18, 1964 United States Patent 3,257,996 TWO-CYCLE INTERNAL COMBUSTION ENGINE Kjell T. J. Henrikson, Hornsgatan 142, Stockholm, Sweden Filed June 18, 1964, Ser. No. 376,619 Claims priority, application Sweden, June 26, 1963, 7,063/ 63 2 Claims. (Cl. 12373) The present invention relates to two-cycle internal combustion engines with the crank chamber as scavenging pump. The objectof the invention is, firstly to increase the amount of scavenging air, and secondly to reduce the loss of fuel through the exhaust ports of the engine cylinder at large amounts of scavenging mixture in engines without fuel injection in the cylinder, while maintaining the mechanical simplicity of the engine.

According to the present invention one or more jet pumps, consisting of driving nozzles, inlet channels and mixing channels, are connected to the transfer ports. The medium pumped by the crank chamber acts as driving medium, when passing from the crank chamber through the jet pumps to the cylinder chamber sucking in extra, fuel-free air through the inlet channels, which are connected with open air.

In engines without fuel injection into the cylinder there are, according to the invention, ports in the piston, which in the 'upper dead centre of the piston coincide with the admission ports of the cylinder. As the mixing channels of the jet pumps are connected to these admission ports, the medium in the mixing channels will be sucked into the crank chamber and replaced by fuel-free air through the inlet channels of the jet pumps. In the upper dead centre of the piston the separate inlet port for the fuelair mixture Will be uncovered as well, at which fuel-air mixture will be sucked into the crank chamber through this port. During the following scavenging process the fuel-free air in the mixing channels will enter the cylinder first, thus making a percentually great part of the fresh mixture escaping through the exhaust ports. The previously known, favourable method of dividing the total scavenging mixture into one fuel-free and one fuelmixed part is thus, according to the invention, accomplished in a mechanically simple way.

According to the invention the driving nozzles of the jet pumps are connected to the crank chamber by ports in the cylinder, and in the piston there are corresponding ports, which in the lower dead centre of the piston coincide with the ports in the cylinder, at which the medium in the crank chamber is pumped through the driving nozzles.

According to the invention the engine as above is combined with an exhaust system, in which an expansion chamber is placed before any silencers. This will reduce the cylinder pressure during the scavenging process, and thus increase the amount of extra air drawn in through the inlet channels of the jet pumps.

The invention is illustrated by way of example in the accompanying drawings, in which FIG. 2 shows a sectional view of the engine. In FIG. 2 the three horizontal sections II, IlIIII and IVIV are marked, and these are shown in FIGS. 1, 3 and 4 respectively.

In the drawings, 1 designates the mixing channels of the jet pumps. To decrease the length of the channels, a number of six channels has been chosen in this example. The total volume of the mixing channels must not exceed the volume sucked into the crank chamber 2 during each revolution, if they are to be completely filled 3,257,996 Patented June 28, 1966 with fuel-free air. The mixing channels 1 end up in the admission ports 4 of the engine cylinder 3.

The driving nozzles 5 of the jet pumps are connected to the ports 7 in the cylinder by the transfer channels 6. The ports 9 in the piston 8 coincide with the ports 7 in the cylinder in the lower dead centre of the piston. Ports 7 and 9 are placed on parts of the circumference where there are no other ports, in this case opposite the exhaust ports 10. The height of ports 7 and 9 is such, that they will be opened somewhat in advance of the admission ports 4. The exhaust ports 10 are placed above the admission ports 4, and their height is such that they will open about 25 degrees before the admission ports 4, compared with 10 degrees normally. This is to prevent the exhaust gases from blowing down into the mixing channels 1.

In the inlet channel 11 of the jet pumps an air regulation means 12 is disposed.

In the lower part of the piston there are ports 13, which in the upper dead centre of the piston coincide with the admission ports 4. Their height is such that the piston, when moving upwards, opens the admission ports 4 and the inlet port 15 of the carburetor 14 simultaneously.

The carburetor is furnished with a throttle valve 17 and a jet 18. The throttle valve 17 is connected to the power regulator of the engine in such a way that it is wide open before the air regulator 12 and the adjustable jet 16 are being opened. This simplifies the adjusting of the jets 16 and 18, because the jet 18 is always Wide open when regulating the adjustable jet 16.

The exhaust pipe 19 is connected to an expansion chamber 20. After the expansion chamber a silencer may be connected.

The construction of the engine can vary, and is by no means limited to these specifications.

I claim:

1. A two-cycle internal combustion engine, including in combination an engine cylinder, a crank chamber at one end of said cylinder, a piston movable in said cylinder to produce, when moving towards said crank chamher, a compression of medium therein, a first port in the wall of said cylinder communicating with a source of fuel-air mixture, a second port in the wall of said cylinder communicating with a number of nozzles forming part of a jet pump having an inlet end and an outlet end, the inlet end of said jet pump being connected with open air, a third port in the wall of said cylinder communicating with the outlet end of said jet pump, a fourth port in the wall of said cylinder communicating with an exhaust system, said first port being open when said piston is in a position near the end of said cylinder remote from said crank chamber to permit sucking in of fuel-air mixture into said crank chamber, a port in said piston connecting said second port with said crank chamber when said piston is in a position near the end of said cylinder next to said crank chamber to permit the fuel air mixture compressed in said crank chamber to pass through said second port, said nozzles and said third port into the part of said cylinder separated from said crank chamber by said piston and to permit sucking in of air through the inlet end of said jet pump, said fourth port being opened in advance of said third port to permit exhaust gases to be let out of said cylinder.

2. A two-cycle internal combustion engine according to claim 1, a second port in said piston, said second port in the piston connecting said third port with said crank chamber when said piston is in a position near the end of said cylinder remote from said crank chamber to per- 3 4 mit sucking in of medium from the outlet end of said jet FOREIGN PATENTS pump into said crank chamber. 613,399 12/1960 Ita1y References Cited by the Examiner Primary Exa'niner.

68 301 $5155 2%? PATENTS 123 73 5 FRED E. ENGELTHALER, Examiner. 8 o nein 1,012,288 12/1911 Stephenson W. E. BURNS, Assistant Exammel.

1,043,254 11/1912 Russell 12373 

1. A TWO-CYCLE INTERNAL COMBUSTION ENGINE, INCLUDING IN COMBINATION AN ENGINE CYLINDER, A CRANK CHAMBER AT ONE END OF SAID CYLINDER, A PISTON MOVABLE IN SAID CYLINDER TO PRODUCE, WHEN MOVING TOWARDS SAID CRANK CHAMBER, A COMPRESSION OF MEDIUM THEREIN, A FIRST PORT IN THE WALL OF SAID CYLINDER COMMUNICATING WITH A SOURCE OF FUEL-AIR MIXTURE, A SECOND PORT IN THE WALL OF SAID CYLINDER COMMUNICATING WITH A NUMBER OF NOZZLES FORMING PART OF A JET PUMP HAVING AN INLET END AND AN OUTLET END, THE INLET END OF SAID JET PUMP BEING CONNECTED WITH OPEN AIR, A THIRD PORT IN THE WALL OF SAID CYLINDER COMMUNICATING WITH THE OUTLET END OF SAID JET PUMP, A FOURTH PORT IN THE WALL OF SAID CYLINDER COMMUNICATING WITH AN EXHAUST SYSTEM, SAID FIRST PORT BEING OPEN WHEN SAID PISTON IS IN A POSITION NEAR THE END OF SAID CYLINDER REMOTE FROM SAID CRANK CHAMBER TO PERMIT SUCKING IN OF FUEL-AIR MIXTURE INTO SAID CRANK CHAMBER, A PORT IN SAID PISTON CONNECTING SAID SECOND PORT WITH SAID CRANK CHAMBER WHEN SAID PISTON IS IN A POSITION NEAR THE END OF SAID CYLINDER NEXT TO SAID CRANK CHAMBER TO PERMIT THE FUEL AIR MIXTURE COM- 